Introduce moderate binding

chrome/android/java_staging/src/org/chromium/chrome/browser/DeferredStartupHandler.java

Index: chrome/android/java_staging/src/org/chromium/chrome/browser/DeferredStartupHandler.java
diff --git a/chrome/android/java_staging/src/org/chromium/chrome/browser/DeferredStartupHandler.java b/chrome/android/java_staging/src/org/chromium/chrome/browser/DeferredStartupHandler.java
index bd54eaa535c10a8bb4bbbac55816a91cd438cbf3..6e157e2d3e897426ff7cd7dd87b1966678060ff6 100644
--- a/chrome/android/java_staging/src/org/chromium/chrome/browser/DeferredStartupHandler.java
+++ b/chrome/android/java_staging/src/org/chromium/chrome/browser/DeferredStartupHandler.java
@@ -4,8 +4,11 @@
 
 package org.chromium.chrome.browser;
 
+import android.content.Context;
 import android.os.AsyncTask;
+import android.text.TextUtils;
 
+import org.chromium.base.FieldTrialList;
 import org.chromium.base.PowerMonitor;
 import org.chromium.base.ThreadUtils;
 import org.chromium.base.TraceEvent;
@@ -20,11 +23,20 @@ import org.chromium.chrome.browser.precache.PrecacheLauncher;
 import org.chromium.chrome.browser.preferences.ChromePreferenceManager;
 import org.chromium.chrome.browser.preferences.privacy.PrivacyPreferencesManager;
 import org.chromium.chrome.browser.share.ShareHelper;
+import org.chromium.components.variations.VariationsAssociatedData;
+import org.chromium.content.browser.ChildProcessLauncher;
 
 /**
  * Handler for application level tasks to be completed on deferred startup.
  */
 public class DeferredStartupHandler {
+    // Constants for trial of moderate binding support.
+    private static final String MODERATE_BINDING_TRIAL_NAME = "MobileModerateBinding";
+    private static final String MODERATE_BINDING_LOW_REDUCE_RATIO_PARAM = "low_reduce_ratio";
+    private static final String MODERATE_BINDING_HIGH_REDUCE_RATIO_PARAM = "high_reduce_ratio";
+    private static final String MODERATE_BINDING_DISABLED_VALUE = "Disabled";
+    private static final float DEFAULT_MODERATE_BINDING_REDUCE_RATIO = 0.25f;
+
     private static DeferredStartupHandler sDeferredStartupHandler;
     private boolean mDeferredStartupComplete;
 
@@ -105,9 +117,43 @@ public class DeferredStartupHandler {
         // Clear any media notifications that existed when Chrome was last killed.
         MediaNotificationService.clearMediaNotifications(application);
 
+        startModerateBindingManagementIfNeeded(application);
+
         mDeferredStartupComplete = true;
     }
 
+    private static void startModerateBindingManagementIfNeeded(Context context) {
+        String trialName = FieldTrialList.findFullName(MODERATE_BINDING_TRIAL_NAME);
+        if (TextUtils.isEmpty(trialName)
+                || MODERATE_BINDING_DISABLED_VALUE.equalsIgnoreCase(trialName)) {

[Alexei Svitkine (slow), 2015/06/17 16:57:22]

Can you make this a param as well?

(Or check StartsWith, but since you're using params already, that's a better
solution.)

This lets you define a Control group that has the same behavior as Disabled,
which is our best practice when you experiment at < 50%.

[Jaekyun Seok (inactive), 2015/06/17 22:31:50]

Done.

+            return;
+        }
+        String lowReduceRatioValue = VariationsAssociatedData.getVariationParamValue(
+                MODERATE_BINDING_TRIAL_NAME, MODERATE_BINDING_LOW_REDUCE_RATIO_PARAM);
+        String highReduceRatioValue = VariationsAssociatedData.getVariationParamValue(
+                MODERATE_BINDING_TRIAL_NAME, MODERATE_BINDING_HIGH_REDUCE_RATIO_PARAM);
+        float lowReduceRatio = DEFAULT_MODERATE_BINDING_REDUCE_RATIO;
+        float highReduceRatio = DEFAULT_MODERATE_BINDING_REDUCE_RATIO * 2;
+        if (!TextUtils.isEmpty(lowReduceRatioValue)) {
+            try {
+                lowReduceRatio = Float.parseFloat(lowReduceRatioValue);
+            } catch (NumberFormatException e) {
+                // Ignore exception.
+            }
+        }
+        if (!TextUtils.isEmpty(highReduceRatioValue)) {

[Alexei Svitkine (slow), 2015/06/17 16:57:22]

Nit: Maybe make a helper function to avoid the extra boilerplate?

[Jaekyun Seok (inactive), 2015/06/17 22:31:50]

Done.

+            try {
+                highReduceRatio = Float.parseFloat(highReduceRatioValue);
+            } catch (NumberFormatException e) {
+                // Ignore exception.
+            }
+        }
+        highReduceRatio = Math.max(0, Math.min(1, highReduceRatio));
+        lowReduceRatio = Math.max(0, Math.min(highReduceRatio, lowReduceRatio));
+        ChildProcessLauncher.startModerateBindingManagement(
+                context, lowReduceRatio, highReduceRatio);
+    }
+
     /**
     * @return Whether deferred startup has been completed.
     */